Are free open source alternatives really all that widely known among the general populous?

I recently began contemplating the influence of open source software after viewing the movie "Revolution OS."  I came to realize that while I had experience using Linux and other open source software, most of my friends had little to no experience with them.  As a Computer Science undergraduate, I have learned to use and appreciate many open source projects, but it seems that most people have not.  The example of Photoshop and GIMP came to my mind.  Ask anybody about Photoshop and they will tell you that it is a program to edit photos, but ask them about GIMP and they will likely have no idea what it is. Photoshop is maintained by Adobe and costs $700 for a full version, whereas GIMP is maintained by the open source community and costs nothing.  For the average consumer, both products can accomplish practically the same things. Why is it, then, that GIMP is not widely known and Photoshop remains the only option in the mind of the consumer?  I think that open source proponents need to be more vocal about the powerful open source options available.  I make it a goal to spread the word whenever I find useful free software.